Volume II: Fundamentals of Injection Molding Series
`
`... material
`selection and
`product design
`fundamentals
`OOUG~ M. BRYCE
`Society of Manufacturing Engineers <@>
`
`•
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`•
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`Am. Honda v. IV II - IPR2018-00619
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`Plastic Injection Molding
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`Plastic Injection Molding
`
`... material selection
`and product design
`fundamentals
`
`By Douglas M. Bryce
`
`Volume II : Fundamentals of
`Injection Moldin g se ries
`
`Published by the
`Society of Manufacturi ng Engineers
`Dearborn , Michigan
`
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`

`

`Copyright © 1997 by Douglas M. Brycc and Socicty of Manufacturing Engineers
`
`9876543
`
`All rights reserved, including those of translation. This book, or parts thereof,
`may not be reproduced in any form or by any means, including photocopying,
`record ing. or microfilming, or by any information storage and retrieval system,
`without permission in writing of the copyright owners.
`
`No liability is assumed by the publisher with respect to the use of information
`contained herein. While every precaution has been taken in the preparation of
`this book, the publis her assumes no responsibility for errors or omissions.
`Publi cation of any data in this book docs not constitute a recommendation or
`endorsement of any patcnt. proprictary right, or product that may be invol ved.
`
`Library of Congress Cat<llog C<lrd Num ber: 97-068807
`International Standard Book Number: 0-87263-488-4
`
`Additional copies may be obtained by contacting:
`
`Society of Manufacturing Engineers
`Customer Service
`One 5MB Drive
`Dearborn, Michigan 48121
`1-800-733-4763
`
`SME staff who participated in producing this book:
`
`Donald A. Peterson, Senior Editor
`Rosemary K. Csizmadia, Production Team Leader
`Dorothy M. Wylo, Production Assistant
`Jennifer L. Courter, Editorial Assistant
`Karen M. Wilhelm, Manager, Reference Publications
`Cover design by Judy D. Munro, Manager, Graphic Services
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`Printed in the United Stales of America
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`
`
`Understanding
`the Injection Molding Process
`
`EVOLUTION OF THE PROCESS
`
`
`
`
`
`
`
`”
`'
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`In 1868, a gentleman by the name of John Wesley Hyatt developed a plastic
`material called celluloid and enteredit in a contest created byabilliard ball
`
`manufacturer. The purpose of the contest was to find a substitute for ivory,
`
`which was becoming expensive and difficult to obtain. Celluloid was actually
`
`qnvented in 1851 by Alexander Parkes, but Hyatt perfected it to where it could
`be processed into a finished form. Heusedit to replace the billiard ball ivory
`and wonthe contest’s grand prize of $10,000, a rich sum in those days. Unfor-
`tunately, after the prize was won, someofthe celluloid billiard balls exploded
`
`on impact during a demonstration (dueto the instability and high flammability
`
`of the material) and further refinement was required to use it in commercial
`ventures. Nonetheless, the plastics industry was born, and it would begin to
`flourish when John Wesley Hyatt andhis brother Isaiah patentedthefirst injec-
`tion molding machine in 1872. They used this machine to injection mold cellu-
`loid plastic. Over the next 40 to 50 years others began to investigate this new
`
`process and expandits application to manufacturing such itemsascollarstays,
`~ buttons, and hair combs. By 1920, the injection molding industry was well en-
`~
`trenched, and it has been boomingeversince.
`
`During the 1940s the industry exploded with a bang (not because of the
`
`instability of celluloid) as World War II created a demand for inexpensive,
`mass-produced products. Néw materials were invented for the process on a
`regular basis, and technical advances resulted in more and more successful
`applications.
`
`
`
`CHARTING INDUSTRY EVOLUTION
`
`
`From its birth in the late 1800s, to recent developments and applications, the
`injection molding industry has grown at a fast and steady rate. It has evolved
`
`from producing combsand buttons to molding products for all production fields,
`
`including automotive, medical, aerospace, and consumer goods, as well as toys,
`plumbing, packaging and construction. Table I-1 lists someof the importantdates
`
`in the evolution of the injection molding industry. Am. Hondav. IV II - IPR2018-00619
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`2 Plastic Injection Molding
`
`
`
`
`
`
`
`
`Table I-1. Evolution of Injection Molding
`1868 John Wesley Hyatt injection-molds celluloid billiard balls.
`1872 John andIsaiah Hyatt patent the injection molding machine.
`
`
`
`1937 Society of the Plastics Industry founded.
`
`
`1938 Dow invents polystyrene(still one of the most popular materials).
`
`
`1940 World WarII events create huge demandfor plastic products,
`
`
`1941 Society of Plastics Engineers founded.
`
`
`1942 Detroit Mold Engineering, Inc. (DME)introduces stock mold base components,
`1946 James Hendry buildsfirst screw injection molding machine.
`
`
`1955 General Electric begins marketing polycarbonate.
`
`
`1959 DuPontintroducesacetal homopolymer.
`
`
`1969 Plastics land on the moon.
`1972 Thefirst parts-removal robotis installed on a molding machine,
`
`
`1979 Plastic production Surpasses steel production.
`1980 Apple uses acrylonitrile-butadiene-styrene (ABS)in theApple Ile computer.
`
`
`1982 The JARVIK-7 Plastic heart keeps BarneyClark alive,
`
`
`1985 Japanesefirm introduces all-electric molding machine,
`
`
`1988 Recycling of plastic comes to age.
`
`
`1990 Aluminum molds introducedfor production injection molding.
`
`1994 Cincinnati-Milacron sellsfirst all-electric machine in U.S.
`
`
`
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`
`
`EVOLUTION OF SCREWCONCEPT
`AND EVALUATION OF PLUNGER
`The machine the Hyatt brothers invented was primitive but performed well for
`their needs. It was simple in that it acted like a large hypodermic needle and
`
`and revolutionized the processing of plastics. Screw machines now account for
`approximately 95% ofall injection machines.
`.
`The auger design of the screw creates a mixing action when new material is
`being readied for injection. The screw is inside the heating cylinder and, when
`activated, mixes the plastic well, creating a homogenized blend ofmaterial. This
`is especially useful when colors are beingmolded or when regrind is being mixed
`with virgin material. After mixing, the screw Stops turning andtheentire screw
`pushes forward, acting like a plungerfor injecting material into a mold.
`Another advantage ofscrew technologyis a reduction ofenergy requirements.
`The injection cylinder that holdstheplastic being readied for the next cycle fea-
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`Understanding the Injection Molding Process 3
`
`at required from the electrical heater bands to soften the plastic to the correct
`he
`ection temperature.
`
`inj
`Although the screw machine is the most popular, there is still a place for the
`
`plunger-type machine. A plunger doesnotrotate;it simply pushes material ahead,
`then retracts for the next cycle.It, too, resides within a heated cylinder. Because
`
`there is no rotating, there is no shearing or mixing action. So, ina plunger ma-
`chine the necessary heating action is provided solely by the external heater bands
`pecause the plunger producesnofriction. Also, if two different colored materials
`are placed together in the heated cylinder they are not blended together. The plunger
`simply injects the materials at the sametime.If, for instance, the two colors are
`white and black, the resultant molded part will take on a marbled appearance
`with definite swirls of black and white throughoutthe part. This may be a desired
`finish for particular products, such as lamp bases or furniture, and the use of a
`plunger machine allowsthat finish to be molded into the product. Use of a screw
`machine would result in a single color (gray) product because the two colors
`would be well mixed priorto injecting.
`‘The injection molding industry has made a huge impactin its short life. Start-
`ing in the workshop of the two Hyatt brothers, it has become a major focus for
`manufacturing of products from toys to medical devices, and most everything in
`between. Thefuture holds only great promise for more productive,cost-effective
`methodsof producing more products using this technology. Improvedmethods,
`materials, processing, and tooling will increase the advantages for product de-
`signers and manufacturers who choose plastic injection molding as their primary
`method of manufacturing.
`
`THE PROCESS
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`ats.
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`ter.
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`I for
`> and
`nto a
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`ial is
`when
`This
`uxed
`Crew
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`ents.
`fea-
`hese
`ause
`pro-
`less
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`njec-
`.
`
`ovice Injection molding is a process in whichaplastic material is heated until it be-
`it for
`comessoft enoughto force into a closed mold, at which point the material cools
`to solidify and form a specific product. The action that takes place is muchlike
`the filling of a jelly donut. A hypodermic-style cylinder and nozzle inject the
`heatedplastic into an opening created in a closed container (mold). The material
`is allowed to harden again, a finished partis ejected, and the cycleis repeated. as
`often as necessary to produce the total numberof pieces required.
`Figure 1-1 showstheactual process in simplified form; in actuality, there are
`more than 100 parameters to be controlled during the process to ensure that a
`quality part is produced in the most economical way. These parameters are dis-
`cussed in detail in Volume I of this series, Plastic Injection Molding...man-
`ufacturing processfundamentals, and should be reviewed by those desiring more
`information. We highlight some of the parameters in this chapter to better ac-
`quaint you with the relationship between the process and the need for proper
`material selection.
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`4 Plastic Injection Molding
`
`
`
`Clamp
`mechanism
`
`Mold halves
`
`Heating
`cylinder
`
`unit
`
`Moving platen —
`
`Stationary platen
`
`Clamp
`unit
`
`Injection
`
`,
`
`Figure 1-1. The injection molding process.
`
`Categorizing the Parameters
`
`First, we must be aware that, although there are so many parametersto control,
`they can be detailed within the confines of four major categories. These are tem-
`perature, pressure, time, and distance as depicted in Figure 1-2.
`Note that the circles in the drawing are interconnected and of different sizes.
`The interconnections indicate that each parameteris both affected by and affects
`other parameters. A change in one may have a major effect on another. The differ-
`ent circle sizes represent the order of importance placed on eachset of param-
`eters; temperature and pressure, for instance, normally are more importantto the
`process than time and distance. Wetake a lookat each of the four categories in
`terms of what’s incorporated within each.
`
`Temperature
`Temperature of the material. The primary temperature of concern is the tem-
`perature to which the plastic material must be heated beforeit is injected into a
`mold. All materials have a range of temperatures within which they are most
`efficiently injected while still maintaining maximum physical properties. For
`amorphousmaterials, (those that soften—not melt—whenheatis applied) this range
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`Temperature
`
`
`
`Understanding the Injection Molding Process 5
`
`
`is rather broad; with crystalline materi-
`als (those that actually melt when heat
`is applied)it is fairly narrow. (Wedis-
`cuss the differences between amorphous
`and crystalline materials in Chapter2).
`With both types of materials, however,
`there is a temperature point at which the
`plastic flowsthe easiest and still main-
`tains proper physical properties. This is
`called the ideal melting point and must
`be attained through educated guesses
`andtrial-and-error. While this may seem
`primitive, it is only required as a fine-
`tuning adjustmentonceaspecific pro-
`duction runis initiated andis finalized
`as part of establishing particular process
`specificationsfor specific products. The
`guessing processactually beginsbyset-
`ting the temperature of the heating cylinder such that the material being injected
`is at a temperature recommended forthat generic material.
`The plastic temperature is measuredas it leaves the heating cylinder to make
`sure it is within the proper range, and then adjusted up or down depending on
`cycle times, required pressures, mold temperature, and a variety of other param-
`eters. These adjustments are made during a pilot run of the process and until
`acceptable parts are produced. When parts meet specifications, a setup sheet is
`created listing the values for all parameters of concern. These valuesare then
`atrol,
`stored for use when that specific job is to run again. Table I-2 shows the recom-
`fem-
`mended melt temperatures for some common materials. These are the temperatures
`.
`that should be referred to when measuringthe material as shownin Figure 1-3.
`TZeS.
`The softening (or melting) of the plastic is achieved by applying heat to the
`fects
`
`fler- plastic material, causing the individual molecules to go into motion. Toapoint,
`fam-
`the more heat that is applied, the faster the molecules move. However, if too
`? the
`much heatis applied, the plastic material begins to degrade and break down into
`“Sn
`its main constituents, one of which is carbon.
`The heatis applied by electrical heater bands wrapped aroundthe outside of the
`heating cylinderof the injection molding machine as depicted in Figure 1-4a.
`The heater bands, which resemble hingedbracelets, are assembled such that
`individual groupsof three or four control the temperature of a single zone. There
`are three basic temperature zonesforthe heating cylinder: rear, center, andfront.
`Each zone is monitored by a thermocouple connectedto a temperature control-
`ler. The thermocouple determines whether ort WondovrelYsthe HAR204829619
`PETHONDA_1009-0009
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`Figure 1-2. Categories of parameters.
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`ae
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`aS
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`toa
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`Table I-2. Suggested Melt Temperatures for Various Plastics
`
`
`Material
`
`Temperature, °F (°C)
`
`
`
`Acetal (COpOLYMeL)00... .eseecessessesssssssessssessessessessssssstessesseseeceececces, 400 (204)
`Acetal (homopolymer) ........ccsccccessssssceseessesessessssesssssseesessescescecee, 425 (218)
`ACTYLIC co seessessessssesssesessecsscsssucsscssaseusansassussussssissssessesseseccescecese. 425 (218)
`Acrylic (modified) oo...ceecccccssescssssssssesecstssesssstssssesseceseeseececcccce, 500 (260)
`ABS (medium-impact) oecccceccsssssseesssessessessssscerseceercesecesece. 400 (204)
`ABS(high-impact and/or flame retardant) sesaseceesseneeseetenseeevenaes 420 (216)
`Cellulose acetate ...ccccsscssssssssstsssssssssesesesesscesesececes“Leveeeseesenees 385 (196)
`Cellulose acetate butyrate2... c.ccccscssecsecesssessecsesssssscsscereesecseess 350 (177)
`Cellulose acetate propionate ........0..c.ccccsscssesscssesssersesecsesseseecccees, 350 (177)
`Ethylene vinyl acetate ..0....ccesccssssssssescesstsssessessssssesseeseescesceseese. 350 (177)
`Liquid crystal polymer ...0......ccccssesssssssssssesesessssssssssesesscerceseese. 500 (260)
`Nylon (Type 6) o....eseeseesscssssessessssscstsssssessssussssssssssssesesesseecesececs, 500 (260)
`Nylon (Type 6/6) ......cesecsssssssssesessscsssssssesssesuesssersssesarsstesssessescees. 525 (274)
`Polyallomer 00.0...eesecsecssessessessecssssucssesessussussssssssssssssaseessereeseess. 485 (252)
`Polyamide-imide oe.eccecsesssessesesssssssssecsessesssesscsssateescesecesees. 650 (343)
`Polyarylate wo...cessssessesstssessecssessssssssssussssssssssssseacaseeseeseescees. 700 (371)
`Polybutylene oo...ececsscssessesessesscsussssecsscsessessessssrssteestecesceseccee, 475 (246)
`Polycarbonate oo...ecececsssesesssssesscssearssssussussssssesseseeseesecceseeccce. 550 (288)
`Polyetheretherketone (PEEK).o....c.cccccscssssssscscsessessecceseecescesece, 720 (382)
`Polyetherimide ..0.....ccseccsscssssesssessesessesesessressereeseesseeseeseseseeas 700 (371)
`Polyethylene (low-density) ..........cccccsssssscsssssssssesceseesecseceececcess. 325 (163)
`Polyethylene (high-density) ........coccoccccsesssssessesssossesesseseoceecece. 400(204)
`Polymethylpentene .0........ccccssessssssssessesscstssscsesssesseteeseccesceseesece. 275 (135)
`Polyphenylene Oxide .......cccecceccccsssssescesecstssressesersesseseesecceseccece. 385 (196)
`Polyphenylene sulfide ........e.cccsessisscsssessstessessecsessecorseeesceeeseece. 575 (302)
`Polypropylene .......ecccssssesssscsvessecsestsasscstsssseesereeecssesseeeneeeseenes 350 (177)
`Polystyrene (general purpOSe) ........ccsccccssessessssssesceseesesseseccessece, 350 (177)
`Polystyrene (medium-impact) 00.....ccecccccsesscssssssesceseeseecececcecsece. 380 (193)
`Polystyrene (high-impact) .......c.ccccccssccssesssesessssscesesvessesceseesece. 390 (199)
`POlySulfOne ooo...eee ceceecsessesssstescssesvesecsussesusaresssssesesseseesecceseecece. 700 (371)
`PVC (Tigi) occ secseecsecsecsecsessvessesstesessessessessessesarssesetceteeseece. 350 (177)
`PVC (flexible) oes eceecsscsesssesssssssusenecsreasssessussessssesesteeeeseescecce. 325 (163)
`Styrene acrylonitrile (SAN) .....c.cccscccsscssssessecssssesvecsescecesceceee. 400 (204)
`Styrene butadiene 00... eecccccccccccssssssssessessssessesscsssesestecceseececceccc., 360 (182)
`Tetrafluorethylene ..0.....eeceeccccescsscsssssessrssestssrssesseesessesseeseseeseecece. 600 (316)
`Thermoplastic polyester (PBT).......cccccccssssssecessceseeseesecceseececscce. 425 (218)
`Thermoplastic polyester (PET) .....0..c.ccecscscssscsscesccssesceseccescescce. 450 (232)
`Urethane elastomer 0...eececccccccccecsssssessessesssssestesessssueeseesesceveesce.. 425 (218)
`
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`
`
`
`
`Hand-held
`
`Molten
`plastic
`
`Nozzle
`
`Figure 1-3. Measuring plastic temperature. -
`
`Center
`
`Barrel
`
`Understanding the Injection Molding Process 7
`
`pyrometer
`Heater band halves Am. Hondav. IV II - IPR2018-00619
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`"EETPerary,
`Ga DEREA WIG;a wawavaw,
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`Ee
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`Nozzle
`assembly
`
`Heater bands
`
`Screw or ram
`
`Nozzle
`tip
`
`Figure 1-4a. The heating cylinder.
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`9 Tlysne MYyeCcHoNn MIOLOING
`
`temperature and, if more heat is required, signals the controller to supply more
`electricity to the heater bands in that temperature zone.
`In addition, the machine nozzle (which is mountedat the front of the heating
`cylinder) incorporates at least one heater and is considered an additional zone
`called the nozzle heater zone. This is depicted in Figure 1-4b.
`
`Nozzle bands
`
`Nozzle assembly
`
`Nozzle
`tip
`
`Figure 1-4b. Nozzle heater zone.
`
`Heatis also generated in the heating cylinder by the compressive force of the
`feed screw turning in the cylinder, Figure 1-5.
`This screw augers fresh material into the heating cylinder from the hopper.
`The turning action squeezes the plastic, thus creating friction, which in turn
`creates heat. The amountoffriction is controlled by a variety of elements such
`as the rotation speed of the screw, and the distance between the outside diam-
`eter of the flights and the body diameter ofthe screw, which changes along the
`length of the screw.
`Temperature of the mold. Another important temperature is that of the mold.
`A mold is used for containing the injected plastic in a specific shape while the
`plastic cools to a solid. After solidifying, the plastic product is ejected from the
`mold and a new cycle is begun.
`.
`The rate at which the plastic cools is an important factor in determining the
`strength of the plastic material’s physical properties, especially with crystalline
`
`
`
`CODOTRODOT
`
`emctoO+
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`
`
`Understanding the Injection Molding Process 9
`
`
`
`Fresh material is brought
`forward to front of barrel
`
`Material pellets
`feeding from hopper
`
`of
`
` oO
`
`
`
`
`
`Material is compressed by the
`flights, resulting in heat from
`the shearing action
`
`Screw rotation causes
`material to auger forward
`along the screw flights
`
`
`i |'||}iii}
`
`Figure 1-5. Cylinder section showing screw action.
`
`plastics. This is because when the material is first heated, the moleculesare dis-
`connected from each other and allowed to move aboutfreely. As the material
`cools, these molecules must attach themselves to each otheragainto regain their
`maximum strength.If they are cooled down too quickly they stop moving before
`they are fully connected andtheresult is a product with less than optimum physi-
`cal strength. So it is important to coolthe plastic at a rate slow enough to allow
`the material to reach proper physical strength, but fast enough to minimize cycle
`time (and total cost). Table I-3 lists recommended mold temperatures for some
`commonplastics.
`Normally, controlling the temperature ofthe mold iis accomplished by running
`water through specially designed channels machinedinto the mold. These chan-
`nels usually consist of a series of holes drilled throughspecific plates that make
`up the mold. These holes are connected, by high-temperature hose, to a tempera-
`ture contro] unit that supplies the appropriate amount and flow of hot or cold
`water to maintain a selected temperature (see Figure 1-6).
`Whenhotter temperatures are required, suchasat start-up time, the tempera-
`ture controller cycles the water through a heating device until the proper tem-
`perature is reached. When cooler temperatures are required, the unit dumps the
`circulating water to drain andrefills itself with water from the input source. In
`this mannerthe unit is capable of maintaining the temperatureof the water circu-
`lating through the moldto within 2 or 3° F (1.1 or 1.7° C).
`
`Temperature of the oil. Most molding machines are drivenEaydraulic
`Systems, although all-electric models are avilablecPNely §syste
`BRaWTGd?
`
`THONDA10
`
`pply more
`
`he heating
`ional zone
`
`
`
`ce of the
`
`> hopper.
`N in turn
`
`nts such
`
`de diam-
`long the
`
`he mold.
`
`Vhile the
`from the
`
`ning the
`ystalline
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`10 Plastic Injection Molding
`
`
`Table I-3. Suggested Mold Temperatures for Various Plastics
`
`
`Material
`
`Temperature, °F (°C)
`
`PETHONDA_1009-0014
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`Acetal (COpOlYMeL)........ccccsccsssscsscsessstsesssssstssssssesatesesevesececeseccece. 200 (93)
`Acetal (homopolymer) .....c.ccccsssscsssessssscssssscesesesesesecesececesecceeece. 210 (99)
`ACTYLIC ooo.eececcscsseseesesescesssesessesesssusscsususavarsusasataarsssavateseseseveceecececes 180 (82)
`Acrylic (modified) ..0.....cccscscscesesscssssssssesesrsscarssessssssasercesecesecceseces 200 (93)
`ABS (medium-impact) .....c.cccccccsccsssesssescsesessscssevesevsteseseseececece. 180 (82)
`ABS(high-impactand/orflame retardant) ..0....c.cccccccscscsessoeeceoseess 185 (85)
`Cellulose acetate 0...ccccscscccssssssssscsssssssesseecssessessvercesesesececcececcec. 150 (66)
`Cellulose acetate butyrate .0....0.c.c.ccccssesessssssesssssssssesseseseseeseeseececcee, 120 (49)
`Cellulose acetate propionate ..........c.cccccecsscsssstsssessesesssestssssesscssesees 120 (49)
`Liquid crystal polymer.........0.0.0.+.sosssscesssssssesesesssusetessssssaveceesee 225 (107)
`Nylon (Type6) 0.0.0...ateseeevsereeseeeseasensesesseseoscassseesesetatesenteetatees 200 (93)
`Nylon (Type 6/6) coeccccsscsssossssssssssssssssssesecsssssssssessssssssivaseessssseeeecece 175 (79)
`Polyallomer oo...ccsesssessssscssesereesesesssssesssssesavesevecsececeessevsatsenes 200 (93)
`Polyamide-imide oo...ececccsccsssesssssssessssesacsessesesssssssesvssseserceseeces 400 (204)
`Polyarylate0... ssssessesssstesesessssssssassrsessessesucsssssscessesevercesesces 275 (135)
`Polybutylene .......ccsssssssscsssesesssssssssesevassssssstsssseseeeeceeceeeeeeccc. 200 (93)
`Polycarbonate..........aeeussaeoessnsensseessenssonsesoacsesssassecnenscsscerssercnnensses 220 (104)
`Polyetheretherketone (PEEK) .........ccccccccssssssecssssesecesccsesececesceses 380 (193)
`Polyetherimide 00... ecsccsssssesesssscsecssestsacsessersssssscsrcrsssesercesesees 225 (107)
`Polyethylene (low-density) .........ccccussscssssessessscssssessesesessecececsecece. 80 (27)
`Polyethylene (high-density) ......c.cccccccsscssssssesssstecssssscssssseserceseess 110 (43)
`Polymethylpentene o0.......cescsssscsssssssessesessesssstssssecrsssaseasssceveeceseees 100 (38)
`Polyphenylene Oxide 0...e.eececcesecsssssssssessessssatsssssacsussessvoussseeceece 140 (60)
`Polyphenylene sulfide ..0......ccccscsssesssssesessssessssessssssseteseceecece, 250 (121)
`Polypropylene o.oo. eesesesesssssssesessessessssssrssessesssseasesssvarceseeesercesese. 120 (49)
`Polystyrene (general purpose) ........c.ccccsscscssesscsesscscsscsseseseecesceceee. 140 (60)
`Polystyrene (medium-impact) ........cecccccesesesssssscsssscesesececeecececccce, 160 (71)
`Polystyrene (high-impact) ......0.cc.ccccessssssssssscsssesesececesececececescecece. 180 (82)
`PolysSulfome oo...ececccsceessssesscscstsseessvsscatasesessssesasassveveteseececcese, 250 (121)
`PVC (Tiga) oescece eceesessesseesesesessessssussusseateresssessssssvsreatesseneuceseee. 140 (60)
`PVC (flexible) ooo. ee ececccsccscssssessssssstsesesssesussearesessesceveresvesceseseese.
`80 (27)
`Styrene acrylonitrile (SAN) ....ccccccccssessesessesesescesseceseseseececececcen. 100 (38)
`Styrene butadiene 2...eccscssssesssssssssssseseessesestssssesscaveesereesecess 100 (38)
`Tetrafluorethylene 0.0.0...cecccccccssssssssscssssssecatssesveseateressesseveceeseecece. 180 (82)
`Thermoplastic polyester (PBT) ........c.cccsscsscessscscsssssessesecceseecescece. 180 (82)
`Thermoplastic polyester (PET) ...c.c.ccccscsccssessssessescessssesseseseccescese, 210 (99)
`
`
`
`Am. Hondav. IV II - IPR2018-0061
`
`Am. Honda v. IV II - IPR2018-00619
`PET_HONDA_1009-0014
`
`

`

`
`
`Understanding the Injection Molding Process 11
`
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`
`
`Mold "A" half
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`
`
`energy for, among other things, turn-
`ing the screw, opening and closing the
`clamp (even in toggle machines), and
`actuating ejector systems. During these
`operations, and even whenthe machine
`is running at idle, the temperature ofthe
`system’s hydraulic fluid rises. This tem-
`perature rise results from friction created
`by the oil flowing through the machine
`and by the compressive force of the oil
`whenusedto provide pressure.
`Oil temperature must be controlled
`to allow it to function properly. If the
`oil is too cool it will be thick and not
`flow easily, which may cause valvesto
`operate sluggishly or notatall. If the
`oil is too hot it will degrade into a thin
`liquid filled with chunksof additive
`materials that broke down because of
`the heat. These clog passageways and
`interrupt operation of the hydraulic
`mechanisms.
`The temperature ofthe oil is con-
`trolled by a heat exchanger. This unit
`circulates the oil over copper (or other
`~ highly-conductive metal) tubing that weaves back and forth inside the unit. The
`tubing is connected to a water inlet and the temperature of the oil is monitored.
`Whentheoil is cold, the heat exchanger doesnot circulate the waterin the tubes.
`The water absorbs heat from the oil as the oil warms up while flowing through
`the hydraulic system. When the oil becomestoo hot, the heat exchanger opens
`the water inlet valve to allow water to circulatethrough the copper tubing. The
`circulating water draws heat from theoil until the oil temperature dropsto the
`proper level. The system then cycles the water off until needed again. In this
`way, the heat exchanger can maintain the proper oil temperature at approxi-
`mately 120° F, +5° F (49° C, +2.7° C).
`
`Mold "B" half
`
`go through mold plates
`
`
`
`
`the pipefittings
`» Hoses connect
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`Drilled and tapped holes
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`Pipe fittings are mounted
`in the tapped holes
`
`Figure 1-6. Controlling temperature of
`mold.
`.
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`
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`Pressure
`
`Pressure is required for a variety of reasons in the injection molding process. We
`will focus on injection pressure, holding pressure, and clamping pressure. Pres-
`sure, for these processes, is provided by the hydraulic oil system within the mold-
`ing machine and a series of control valves, regulators, and directional valves. The
`system normally provides a primary “line” pressung,pfRAD psivlf0.PRevEm2)06 19
`PETHONDA_1009-0015
`
`
`
`Am. Honda v. IV II - IPR2018-00619
`PET_HONDA_1009-0015
`
`

`

`
`
`12 Plastic Injection Molding
`
`
`<—_—_———. Weight
`
`Piston
`
`cylinder .
`
`whichis then adjusted up or downbythe control components of the system to
`provide whateverpressure is neededfor a particular application. Forinstance, the
`injection pressure can be adjusted from approximately 500 psi (35.2 kg/cm?) for
`fast-flowingplastic, up to 20,000 psi (1406.1 kg/cm?) for highly viscous materials.
`The specific requirements for the various pressure applicationsfollow.
`Injection pressure. Injection pressure is the primary pressure used for the
`injection molding process.It can be defined as the amount of pressure required to
`produce the initial filling of the mold cavity image. (The cavity imageis the
`opening in the mold that will be filled with plastic to form the product being
`molded.) Note that we use the phrase initial filling. Initial filling represents ap-
`proximately 95% ofthe totalfilling of the cavity image.
`The amountof pressure required will range from very low (500 psi [35.2 kg/
`cm?]) to very high (20,000 psi [1,406.1 kg/cm?]). What determines how much
`pressure is usedis the viscosity and flow rate of the plastic being injected. Of the
`more than 20,000 plastic materials available today, mostwill fall within a pres-
`sure range requirementof approximately 5000 to 15,000 psi (351.5 to 1054.6 kg/
`cm?). And most of these will have a flow index rating of between 5 and 20.
`The flow index rating (properly re-
`ferred to as the melt index) is a value
`designating the amount of material in
`gramsthat flows over a 10-minute pe-
`riod from a specially designed rheom-
`eter. This is an official ASTM standard,
`number D-1238, andis depicted in Fig-
`ure 1-7.
`.
`The melt index (MI)test is a good
`reference test to determine the relative
`thickness (viscosity) of a plastic mate-
`rial, and therebyits relative ease of flow
`during the injection process. An MI of
`around 5 indicates a very viscous ma-
`terial and requires molding pressures
`that are very high. On the other hand,
`materials with an MIof 20 are easy to
`mold and require low pressures. The
`materials data sheet supplied by the
`manufacturer indicates the melt index
`range for a specific material.
`Of importancehereis that the melt
`index also indicates the properties of
`the plastic material being tested.
`Table I-4 shows some of these indi-
`cations.
`Am. Higdtev! W MeltpRdet sheaméter.
`PETHONDA.1009-0016
`
`Heated
`
`<_—_—— Extrudate
`
`Am. Honda v. IV II - IPR2018-00619
`PET_HONDA_1009-0016
`
`

`

`The Language of Plastics 2
`
`DEFINITIONS RELATlNG TO MATE RIALS
`
`In this chapter we prov ide definitions fo r Ihe various terms Ihul arc uniq ue to
`plastic materials. These descriptions arc important because they help in the dcc i(cid:173)
`sion-nUlking process for selecting the proper material o r family of mllleri<l!s 10
`provide the required properties for a specific product and process. We start with
`the most pervlIsive term. plastic.
`
`The Delinition of IJlastic
`
`A simplistic definition of plastic (us used to dcsnibe molding materials) might be:
`Any complex, organic, l)oiymcril.ed compmllld capable of beillg
`~'IU/ped or/ormed.
`Generally speaking, the terms "plastic" and "polymer" aTC used interchange(cid:173)
`ably. although strictly speilk ing a polymer is a plastic, but a plastic does not have
`to be a polymer. Plastics can be in the form of liq uids or solids or something
`between the two.
`Plastics are created by refini ng common petroleum products, crude oil and
`natural gas bei ng the main building blocks. Figure 2- 1 is a diagram of how these
`blocks are utilized in making some of the more com mon plastic materials avail(cid:173)
`able today. Experimental work is currently underway to create plastic materials
`from sources other than petroleum, with limited Sllccess recorded in creating pri(cid:173)
`mary materials from stich products as vegetable oils and coat.
`
`Pol ym erization
`
`When we discllSs plostics we arc usually re ferri ng to compou nds that have bcen
`created by way of a process called polymeriwtioll, defincd as:
`A reaction caused by combilling mOl/omer wili! (I catalyst, /lllder pres(cid:173)
`sure, and wili! hear.
`A monolller is a single unit. In the polymerization process we combine many
`single units of plastic into many combined units o f plastic, known as polymer.f.
`Therefor